DC Load Regulation and AC Ripple
PSU Testing Methodology
Establishing an accurate load is critical to testing and evaluating a PC power supply. PCPerspective’s power supply test bench can place a precise DC load on the PSU under test. Each power supply is tested under controlled, demanding conditions up to its maximum rated load (at 40ºC). Our current suite of tests includes:
• DC Load Regulation
• AC Ripple and Noise
• Differential Temperature
The FSP Hydro G 850W power supply was evaluated on both features and performance. A full range of equipment was used to test the power supply under controlled load conditions.
• (2) CSI3710A Programmable DC load (+3.3V and +5V outputs)
• (4) CSI3711A Programmable DC load (+12V)
• (3) 218W Precision resistor load bank (+12V)
• Switchable precision resistor load bank (-12V and +5VSB)
• Agilent 34401A digital multimeter (Accuracy ±0.0035% vDC)
• Extech 380803 Power Analyzer (Accuracy ±0.5% of full scale)
• DS1M12 "StingRay" digital oscilloscope (20M S/s with 12 Bit ADC)
• Powerstat Variable Autotransformer, 1.4 KVA, 0-140 VAC
• Extech Model 407738 digital sound level meter (Accuracy ±1.5 dB)
The following cables/connectors were used to connect the power supply to the PCPerspective power supply test equipment.
• (1) 20+4 pin ATX
• (1) 8-pin EPS/ATX12V
• (6) 6-pin PCI-E
• (2) SATA
• (2) Molex
DC Output Load Regulation
To simulate demanding and maximum loading conditions, the power supply was connected to the load testers and supplied with a constant 120 VAC. In this test we are interested in seeing how well a PSU can maintain the various output voltages while operating under different loads.
The ATX12V V2.2 tolerance for voltages states how much each output (rail) is allowed to fluctuate and has tighter tolerances now for the +12V outputs. I have also included a second table of expanded tolerances (±1% to ±6%) for reference.
The following tables list the DC voltage results for the PSU while operating on 120 VAC, 60 Hz.
The Hydro G 850W power supply produced very good voltage regulation on all of the DC outputs while delivering the full rated 850 watts total load. All of the primary rails stayed within 2% load regulation and the all-important +12V output only dropped 0.09V. Very good.
AC Ripple and Noise on the DC Outputs
The amount of AC ripple and noise present on the DC outputs was checked using a digital oscilloscope. This AC component may be present in the KHz range where most switching power supplies operate or it may be more prevalent at the 60 Hz line frequency. We adjust the O-scope time base to look for AC ripple at both low and high frequencies. The ATX12V V2.2 specification for DC output noise/ripple is defined in the ATX12V Power Supply Design Guide.
Ideally we would like to see no AC ripple (repetitive) or noise (random) on the DC outputs – the cleaner the better! But in reality there will always be some present. I measured the amplitude of the AC signal (in millivolts, peak-to-peak) to see how well the power supply complied with the ATX standard. The following table lists the ripple/noise results during all of the load tests for the main output voltages of interest.
The Hydro G 850W power supply exhibited very good AC ripple and noise suppression across the full range of loads.
Why would you brand something
Why would you brand something “Hydro” when it has no provision for watercooling? We sadly haven’t seen a WC-capable PSU for quite some time.
There hasnt been a need for
There hasnt been a need for watercooling PSU these days with higher efficiency components used.
For ATX monsters maybe, but
For ATX monsters maybe, but if you want something more compact (e.g. SFX, FlexATX) where you are limited in maximum fan size by case dimensions, being able to offload cooling for the system to a central radiator is a huge benefit for noise and case volume.
maybe it’s me, but using
maybe it’s me, but using water as a name for a power supply just doesn’t sound right.
I thought maybe it was a
I thought maybe it was a liquid cooled power supply. Just what I need in my system, more radiators and fans.
In fact FSP already has
In fact FSP already has liquid cooled PSU and it is called HYYDRO PTM+
Just a note if anyone is
Just a note if anyone is reading this, I bought this PSU a week ago and it came with two 8 pin CPU connectors.Both on one cable, first one is 8 pin, second is 4+4. Around 15 cm between them.